A. Magic Numbers
time limit per test2 seconds

memory limit per test256 megabytes

inputstandard input

outputstandard output

A magic number is a number formed by concatenation of numbers 1, 14 and 144. We can use each of these numbers any number of times. Therefore 14144, 141414 and 1411 are magic numbers but 1444, 514 and 414 are not.

You’re given a number. Determine if it is a magic number or not.

Input

The first line of input contains an integer n, (1 ≤ n ≤ 109). This number doesn’t contain leading zeros.

Output
Print “YES” if n is a magic number or print “NO” if it’s not.

Examples

input
114114

output
YES

input
1111

output
YES

input
441231

output
NO

My Answer Code:

#include<bits/stdc++.h>
using namespace std;
int main()
{ 
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    string s;
    cin>>s;
    for(int i=0;i<s.length();i++)
    { 
        if((s[i]!='1'&&s[i]!='4')||s[0]!='1'){ cout<<"NO"<<'\n';return 0;}
    }
    for(int i=0;i+2<s.length();i++)
    { 
        if(s[i]=='4'&&s[i+1]=='4'&&s[i+2]=='4'){ cout<<"NO"<<'\n';return 0;}
    }
    cout<<"YES"<<'\n';
    return 0;
}